It is well known to use fiber optic systems to carry optical signals. Optical signals can be characterized as including optical energy, and optical signals may additionally include information, such as data, audio or video information.
Fiber optic systems have a number of features that make them superior, in some applications, to systems that use traditional copper cables, or the like. For example, fiber optic systems can have a much larger information-carrying capacity and are not subject to electrical interference. In addition, signals transmitted over long-distance optic fibers need less amplification tham do signals transmitted over copper cables of equal length.
In a fiber optic system, it is typical for two optic fibers to be fused in an end-to-end arrangement to provided a continuous length of optic fiber. It is also common for optic fibers to be fused in a side-by-side arrangement, in which an elongate section of one optic fiber is fused to an elongate section of another optic fiber so that optical signals are transferred between the fused fibers. Such a side-by-side fused optical interface, which can be characterized as a passive fusion coupler, allows for good transfer of optical signals between the fused optic fibers, but provides no control over the direction of transfer and little or no control over the amount of optical energy transferred. Whereas it may be desired for optical signals to be transferred only from a first of the fused optic fibers to a second of the fused optic fibers in a passive fusion coupler, optical signals may also be transferred in the opposite, undesired direction, i.e., from the second optic fiber to the first optic fiber. Thus, passive fusion couplers are disadvantageous in some applications, such as where it is desired to use a single coupler to transmit optical signals via an optical path and receive optical signals from the same path while keeping any of the transmitted signals separate from the received signals.
It is also common for fiber optic systems to include powered couplers. A powered coupler includes an optical receiver, such as a photo detector, that receives optical signals, converts the optical signals into electronic data, and supplies the electronic data to another powered coupler that transmits optical signals. Whereas powered couplers can detect information on one optic fiber and transmit the information on another optic fiber, some aspects of the original optical signals may be lost in the transfer, such as the energy level, frequency or amplitude of the original optical signal, which can be disadvantageous in some applications.